Add strbuf_append_number()

The separate strbuf_append_number() function avoids a potential double
call to the slow vsnprintf() function required by strbuf_append_fmt().

Also inline strbuf_append_mem() since it is very simple and will
be used often.

2 files changed, 27 insertions, 8 deletions

diff --git a/strbuf.c b/strbuf.c
index b6227fc..7a53a52 100644
--- a/strbuf.c
+++ b/strbuf.c
@@ -175,13 +175,6 @@ void strbuf_resize(strbuf_t *s, int len)
     s->reallocs++;
 }
 
-void strbuf_append_mem(strbuf_t *s, const char *c, int len)
-{
-    strbuf_ensure_empty_length(s, len);
-    memcpy(s->buf + s->length, c, len);
-    s->length += len;
-}
-
 void strbuf_append_string(strbuf_t *s, const char *str)
 {
     int space, i;
@@ -200,6 +193,24 @@ void strbuf_append_string(strbuf_t *s, const char *str)
     }
 }
 
+void strbuf_append_number(strbuf_t *s, double number)
+{
+    int len;
+
+    /* Lowest double printed with %.14g is 21 characters long:
+     * -1.7976931348623e+308
+     *
+     * Use 32 to include the \0, and a few extra just in case..
+     */
+    strbuf_ensure_empty_length(s, 32);
+
+    len = sprintf(s->buf + s->length, "%.14g", number);
+    if (len < 0)
+        die("BUG: Unable to convert number");  /* This should never happen.. */
+
+    s->length += len;
+}
+
 void strbuf_append_fmt(strbuf_t *s, const char *fmt, ...)
 {
     va_list arg;
diff --git a/strbuf.h b/strbuf.h
index 9b662ef..46fad33 100644
--- a/strbuf.h
+++ b/strbuf.h
@@ -66,8 +66,9 @@ static  void strbuf_ensure_empty_length(strbuf_t *s, int len);
 
 /* Update */
 extern void strbuf_append_fmt(strbuf_t *s, const char *format, ...);
-extern void strbuf_append_mem(strbuf_t *s, const char *c, int len);
+static void strbuf_append_mem(strbuf_t *s, const char *c, int len);
 extern void strbuf_append_string(strbuf_t *s, const char *str);
+extern void strbuf_append_number(strbuf_t *s, double number);
 static void strbuf_append_char(strbuf_t *s, const char c);
 static void strbuf_ensure_null(strbuf_t *s);
 
@@ -100,6 +101,13 @@ static inline void strbuf_append_char_unsafe(strbuf_t *s, const char c)
     s->buf[s->length++] = c;
 }
 
+static inline void strbuf_append_mem(strbuf_t *s, const char *c, int len)
+{
+    strbuf_ensure_empty_length(s, len);
+    memcpy(s->buf + s->length, c, len);
+    s->length += len;
+}
+
 static inline void strbuf_ensure_null(strbuf_t *s)
 {
     s->buf[s->length] = 0;